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@@ -0,0 +1,429 @@
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+/*
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+ * jump label support
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+ *
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+ * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
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+ *
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+ */
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+#include <linux/jump_label.h>
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+#include <linux/memory.h>
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+#include <linux/uaccess.h>
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+#include <linux/module.h>
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+#include <linux/list.h>
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+#include <linux/jhash.h>
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+#include <linux/slab.h>
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+#include <linux/sort.h>
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+#include <linux/err.h>
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+
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+#ifdef HAVE_JUMP_LABEL
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+
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+#define JUMP_LABEL_HASH_BITS 6
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+#define JUMP_LABEL_TABLE_SIZE (1 << JUMP_LABEL_HASH_BITS)
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+static struct hlist_head jump_label_table[JUMP_LABEL_TABLE_SIZE];
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+
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+/* mutex to protect coming/going of the the jump_label table */
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+static DEFINE_MUTEX(jump_label_mutex);
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+
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+struct jump_label_entry {
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+ struct hlist_node hlist;
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+ struct jump_entry *table;
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+ int nr_entries;
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+ /* hang modules off here */
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+ struct hlist_head modules;
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+ unsigned long key;
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+};
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+
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+struct jump_label_module_entry {
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+ struct hlist_node hlist;
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+ struct jump_entry *table;
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+ int nr_entries;
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+ struct module *mod;
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+};
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+
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+static int jump_label_cmp(const void *a, const void *b)
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+{
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+ const struct jump_entry *jea = a;
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+ const struct jump_entry *jeb = b;
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+
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+ if (jea->key < jeb->key)
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+ return -1;
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+
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+ if (jea->key > jeb->key)
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+ return 1;
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+
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+ return 0;
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+}
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+
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+static void
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+sort_jump_label_entries(struct jump_entry *start, struct jump_entry *stop)
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+{
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+ unsigned long size;
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+
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+ size = (((unsigned long)stop - (unsigned long)start)
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+ / sizeof(struct jump_entry));
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+ sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
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+}
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+
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+static struct jump_label_entry *get_jump_label_entry(jump_label_t key)
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+{
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+ struct hlist_head *head;
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+ struct hlist_node *node;
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+ struct jump_label_entry *e;
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+ u32 hash = jhash((void *)&key, sizeof(jump_label_t), 0);
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+
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+ head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)];
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+ hlist_for_each_entry(e, node, head, hlist) {
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+ if (key == e->key)
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+ return e;
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+ }
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+ return NULL;
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+}
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+
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+static struct jump_label_entry *
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+add_jump_label_entry(jump_label_t key, int nr_entries, struct jump_entry *table)
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+{
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+ struct hlist_head *head;
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+ struct jump_label_entry *e;
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+ u32 hash;
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+
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+ e = get_jump_label_entry(key);
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+ if (e)
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+ return ERR_PTR(-EEXIST);
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+
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+ e = kmalloc(sizeof(struct jump_label_entry), GFP_KERNEL);
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+ if (!e)
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+ return ERR_PTR(-ENOMEM);
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+
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+ hash = jhash((void *)&key, sizeof(jump_label_t), 0);
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+ head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)];
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+ e->key = key;
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+ e->table = table;
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+ e->nr_entries = nr_entries;
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+ INIT_HLIST_HEAD(&(e->modules));
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+ hlist_add_head(&e->hlist, head);
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+ return e;
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+}
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+
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+static int
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+build_jump_label_hashtable(struct jump_entry *start, struct jump_entry *stop)
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+{
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+ struct jump_entry *iter, *iter_begin;
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+ struct jump_label_entry *entry;
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+ int count;
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+
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+ sort_jump_label_entries(start, stop);
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+ iter = start;
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+ while (iter < stop) {
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+ entry = get_jump_label_entry(iter->key);
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+ if (!entry) {
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+ iter_begin = iter;
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+ count = 0;
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+ while ((iter < stop) &&
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+ (iter->key == iter_begin->key)) {
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+ iter++;
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+ count++;
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+ }
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+ entry = add_jump_label_entry(iter_begin->key,
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+ count, iter_begin);
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+ if (IS_ERR(entry))
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+ return PTR_ERR(entry);
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+ } else {
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+ WARN_ONCE(1, KERN_ERR "build_jump_hashtable: unexpected entry!\n");
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+ return -1;
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+ }
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+ }
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+ return 0;
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+}
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+
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+/***
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+ * jump_label_update - update jump label text
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+ * @key - key value associated with a a jump label
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+ * @type - enum set to JUMP_LABEL_ENABLE or JUMP_LABEL_DISABLE
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+ *
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+ * Will enable/disable the jump for jump label @key, depending on the
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+ * value of @type.
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+ *
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+ */
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+
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+void jump_label_update(unsigned long key, enum jump_label_type type)
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+{
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+ struct jump_entry *iter;
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+ struct jump_label_entry *entry;
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+ struct hlist_node *module_node;
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+ struct jump_label_module_entry *e_module;
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+ int count;
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+
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+ mutex_lock(&jump_label_mutex);
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+ entry = get_jump_label_entry((jump_label_t)key);
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+ if (entry) {
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+ count = entry->nr_entries;
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+ iter = entry->table;
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+ while (count--) {
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+ if (kernel_text_address(iter->code))
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+ arch_jump_label_transform(iter, type);
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+ iter++;
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+ }
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+ /* eanble/disable jump labels in modules */
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+ hlist_for_each_entry(e_module, module_node, &(entry->modules),
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+ hlist) {
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+ count = e_module->nr_entries;
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+ iter = e_module->table;
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+ while (count--) {
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+ if (kernel_text_address(iter->code))
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+ arch_jump_label_transform(iter, type);
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+ iter++;
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+ }
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+ }
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+ }
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+ mutex_unlock(&jump_label_mutex);
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+}
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+
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+static int addr_conflict(struct jump_entry *entry, void *start, void *end)
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+{
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+ if (entry->code <= (unsigned long)end &&
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+ entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
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+ return 1;
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+
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+ return 0;
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+}
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+
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+#ifdef CONFIG_MODULES
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+
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+static int module_conflict(void *start, void *end)
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+{
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+ struct hlist_head *head;
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+ struct hlist_node *node, *node_next, *module_node, *module_node_next;
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+ struct jump_label_entry *e;
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+ struct jump_label_module_entry *e_module;
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+ struct jump_entry *iter;
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+ int i, count;
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+ int conflict = 0;
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+
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+ for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
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+ head = &jump_label_table[i];
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+ hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
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+ hlist_for_each_entry_safe(e_module, module_node,
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+ module_node_next,
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+ &(e->modules), hlist) {
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+ count = e_module->nr_entries;
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+ iter = e_module->table;
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+ while (count--) {
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+ if (addr_conflict(iter, start, end)) {
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+ conflict = 1;
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+ goto out;
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+ }
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+ iter++;
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+ }
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+ }
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+ }
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+ }
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+out:
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+ return conflict;
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+}
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+
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+#endif
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+
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+/***
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+ * jump_label_text_reserved - check if addr range is reserved
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+ * @start: start text addr
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+ * @end: end text addr
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+ *
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+ * checks if the text addr located between @start and @end
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+ * overlaps with any of the jump label patch addresses. Code
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+ * that wants to modify kernel text should first verify that
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+ * it does not overlap with any of the jump label addresses.
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+ *
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+ * returns 1 if there is an overlap, 0 otherwise
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+ */
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+int jump_label_text_reserved(void *start, void *end)
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+{
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+ struct jump_entry *iter;
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+ struct jump_entry *iter_start = __start___jump_table;
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+ struct jump_entry *iter_stop = __start___jump_table;
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+ int conflict = 0;
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+
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+ mutex_lock(&jump_label_mutex);
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+ iter = iter_start;
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+ while (iter < iter_stop) {
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+ if (addr_conflict(iter, start, end)) {
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+ conflict = 1;
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+ goto out;
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+ }
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+ iter++;
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+ }
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+
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+ /* now check modules */
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+#ifdef CONFIG_MODULES
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+ conflict = module_conflict(start, end);
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+#endif
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+out:
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+ mutex_unlock(&jump_label_mutex);
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+ return conflict;
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+}
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+
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+static __init int init_jump_label(void)
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+{
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+ int ret;
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+ struct jump_entry *iter_start = __start___jump_table;
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+ struct jump_entry *iter_stop = __stop___jump_table;
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+ struct jump_entry *iter;
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+
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+ mutex_lock(&jump_label_mutex);
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+ ret = build_jump_label_hashtable(__start___jump_table,
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+ __stop___jump_table);
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+ iter = iter_start;
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+ while (iter < iter_stop) {
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+ arch_jump_label_text_poke_early(iter->code);
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+ iter++;
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+ }
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+ mutex_unlock(&jump_label_mutex);
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+ return ret;
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+}
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+early_initcall(init_jump_label);
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+
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+#ifdef CONFIG_MODULES
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+
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+static struct jump_label_module_entry *
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+add_jump_label_module_entry(struct jump_label_entry *entry,
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+ struct jump_entry *iter_begin,
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+ int count, struct module *mod)
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+{
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+ struct jump_label_module_entry *e;
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+
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+ e = kmalloc(sizeof(struct jump_label_module_entry), GFP_KERNEL);
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+ if (!e)
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+ return ERR_PTR(-ENOMEM);
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+ e->mod = mod;
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+ e->nr_entries = count;
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+ e->table = iter_begin;
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+ hlist_add_head(&e->hlist, &entry->modules);
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+ return e;
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+}
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+
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+static int add_jump_label_module(struct module *mod)
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+{
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+ struct jump_entry *iter, *iter_begin;
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+ struct jump_label_entry *entry;
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+ struct jump_label_module_entry *module_entry;
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+ int count;
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+
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+ /* if the module doesn't have jump label entries, just return */
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+ if (!mod->num_jump_entries)
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+ return 0;
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+
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+ sort_jump_label_entries(mod->jump_entries,
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+ mod->jump_entries + mod->num_jump_entries);
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+ iter = mod->jump_entries;
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+ while (iter < mod->jump_entries + mod->num_jump_entries) {
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+ entry = get_jump_label_entry(iter->key);
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+ iter_begin = iter;
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+ count = 0;
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+ while ((iter < mod->jump_entries + mod->num_jump_entries) &&
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+ (iter->key == iter_begin->key)) {
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+ iter++;
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+ count++;
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+ }
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+ if (!entry) {
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+ entry = add_jump_label_entry(iter_begin->key, 0, NULL);
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+ if (IS_ERR(entry))
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+ return PTR_ERR(entry);
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+ }
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+ module_entry = add_jump_label_module_entry(entry, iter_begin,
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+ count, mod);
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+ if (IS_ERR(module_entry))
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+ return PTR_ERR(module_entry);
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+ }
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+ return 0;
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+}
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+
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+static void remove_jump_label_module(struct module *mod)
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+{
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+ struct hlist_head *head;
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+ struct hlist_node *node, *node_next, *module_node, *module_node_next;
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+ struct jump_label_entry *e;
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+ struct jump_label_module_entry *e_module;
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+ int i;
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+
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+ /* if the module doesn't have jump label entries, just return */
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+ if (!mod->num_jump_entries)
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+ return;
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+
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+ for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
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+ head = &jump_label_table[i];
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+ hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
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+ hlist_for_each_entry_safe(e_module, module_node,
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+ module_node_next,
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+ &(e->modules), hlist) {
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+ if (e_module->mod == mod) {
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+ hlist_del(&e_module->hlist);
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+ kfree(e_module);
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+ }
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+ }
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+ if (hlist_empty(&e->modules) && (e->nr_entries == 0)) {
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+ hlist_del(&e->hlist);
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+ kfree(e);
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+ }
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+ }
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|
+ }
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+static int
|
|
|
|
+jump_label_module_notify(struct notifier_block *self, unsigned long val,
|
|
|
|
+ void *data)
|
|
|
|
+{
|
|
|
|
+ struct module *mod = data;
|
|
|
|
+ int ret = 0;
|
|
|
|
+
|
|
|
|
+ switch (val) {
|
|
|
|
+ case MODULE_STATE_COMING:
|
|
|
|
+ mutex_lock(&jump_label_mutex);
|
|
|
|
+ ret = add_jump_label_module(mod);
|
|
|
|
+ if (ret)
|
|
|
|
+ remove_jump_label_module(mod);
|
|
|
|
+ mutex_unlock(&jump_label_mutex);
|
|
|
|
+ break;
|
|
|
|
+ case MODULE_STATE_GOING:
|
|
|
|
+ mutex_lock(&jump_label_mutex);
|
|
|
|
+ remove_jump_label_module(mod);
|
|
|
|
+ mutex_unlock(&jump_label_mutex);
|
|
|
|
+ break;
|
|
|
|
+ }
|
|
|
|
+ return ret;
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+/***
|
|
|
|
+ * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
|
|
|
|
+ * @mod: module to patch
|
|
|
|
+ *
|
|
|
|
+ * Allow for run-time selection of the optimal nops. Before the module
|
|
|
|
+ * loads patch these with arch_get_jump_label_nop(), which is specified by
|
|
|
|
+ * the arch specific jump label code.
|
|
|
|
+ */
|
|
|
|
+void jump_label_apply_nops(struct module *mod)
|
|
|
|
+{
|
|
|
|
+ struct jump_entry *iter;
|
|
|
|
+
|
|
|
|
+ /* if the module doesn't have jump label entries, just return */
|
|
|
|
+ if (!mod->num_jump_entries)
|
|
|
|
+ return;
|
|
|
|
+
|
|
|
|
+ iter = mod->jump_entries;
|
|
|
|
+ while (iter < mod->jump_entries + mod->num_jump_entries) {
|
|
|
|
+ arch_jump_label_text_poke_early(iter->code);
|
|
|
|
+ iter++;
|
|
|
|
+ }
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+struct notifier_block jump_label_module_nb = {
|
|
|
|
+ .notifier_call = jump_label_module_notify,
|
|
|
|
+ .priority = 0,
|
|
|
|
+};
|
|
|
|
+
|
|
|
|
+static __init int init_jump_label_module(void)
|
|
|
|
+{
|
|
|
|
+ return register_module_notifier(&jump_label_module_nb);
|
|
|
|
+}
|
|
|
|
+early_initcall(init_jump_label_module);
|
|
|
|
+
|
|
|
|
+#endif /* CONFIG_MODULES */
|
|
|
|
+
|
|
|
|
+#endif
|